NEW YORK (CNN) --Five years ago, in his book "Shakespeare: The Invention of the Human," Harold Bloom explored the authorship of the Hamlet saga in a text he referred to as the "Ur-Hamlet." The idea was to trace the genesis of the play and deal with the questions of Shakespeare's authorship, a hotly debated issue among some scholars.

In focusing so intently on the play's roots, however, he felt he missed the play itself.

That drove him back to the much-discussed work about the troubled Prince of Denmark, whose father is murdered and whose mother marries the murderer -- Hamlet's uncle. What emerged was Bloom's new book, "Hamlet: Poem Unlimited" (Riverhead). (The title is from Polonius in Act II.)

"I had become so obsessed with the question of the 'Ur-Hamlet' that most of what I thought I felt and understood about the mature 'Hamlet' we know was set aside," he said in a phone interview from his home in Connecticut. "So I wrote this to make up for that, but also because I felt that I had understood aspects of the mature play better and better, and I wanted to put them in one place."

Enduring character

Of course, in order to dig into the play, Bloom once again had to discuss its roots -- which predate its first performance about 1600.

"Nobody has ever seen the 'Ur-Hamlet,' " Bloom said, adding that the play's existence is documented by the writings of Shakespeare's contemporary Thomas Nash. The first play, he added, was written between 1587 and 1589, around the time of "Two Gentlemen of Verona" and "Titus Andronicus."

"The real 'Hamlet' is of course later, first performed in 1600, then performed with revisions in 1601, and eventually included in the First Folio after Shakespeare's death," Bloom continued. "It really has more in common with the two major works it comes between, the two great comedies 'As You Like It' and 'Twelfth Night'."

But the meat of Bloom's work is in its discussion of the central character, an endless source of interpretation for 400 years of actors and scholars. Was he insane? Did he merely act that way? Was his famed indecision part of his personality or a contrived creation?

... and Ethan Hawke played him as the son of a 20th-century business executive in a 2000 film version.

Bloom analyzes Hamlet -- and "Hamlet" -- with segments briefly laid out following particular lines of the play (for those who are interested, Bloom used the current Arden edition of "Hamlet"). In general, what emerges is a celebration of Hamlet as an enduring character of singular charisma, imbued with an intelligence that transcends Shakespeare himself.

For Bloom, Hamlet represents the gateway to the modern sense of selfhood. "Hamlet's will loses the name of action, but not the true nature of action which abides in the exaltation of mind ... as this grandest of consciousnesses overhears its own cognitive music," he writes.

And the character's inscrutability is his source of charisma, he continues. "Hamlet throughout, but particularly after his return from the sea, knows something we want and need to know, and part of his play's power over us is that we ransack it hoping to find out the secret," he writes.

'There's no end to Hamlet'

The indefatigable Bloom draws on his varied knowledge for "Hamlet: Poem Unlimited." The distinguished humanities scholar has held positions at Harvard, Yale, and NYU, and penned more than 20 books, on topics ranging from the Western canon to the Kabbala.

By pointing out that Hamlet's mind is turned back onto itself, some may believe that Bloom is implying that the character is mentally ill, stuck in his own echo chamber. He disagreed. The fascination with Hamlet's mind, he said, indicates merely that the character has an infinite depth -- and an infinite ability to change.

"There's no end to Hamlet, as Goethe said of Shakespeare in general. He really compels you to relate him to everything you know," he said.

Author Harold Bloom

"I cannot think of another literary dramatic character who has anything like Hamlet's sheer intelligence, who is so original a mind, and who is actually endowed by Shakespeare with a kind of authorial consciousness ... so that you can start quoting Hamlet the way you quote Nietzsche, or Emerson, or Freud, or Montaigne on almost any subject," he said.

"So he really has a kind of cognitive music that he hears all the time, and he is in a perpetual state of change because of it, because he is, as Dr. Samuel Johnson first said, the most serious and volatile of Shakesperian protagonists."